Axle Assembly Shoulder Joint Fluid Churning Reduction
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Solution Overview
Problem
Traditional axle assemblies for front drive steer axles face challenges in reducing lubricating fluid churning and heat generation in shoulder joints, leading to increased parasitic losses.
Innovation Solution
The axle assembly incorporates a drive shaft with bevel gears and a non-horizontal driven shaft within a shoulder structure, where the drive shaft is connected to a differential housing, and the shoulder structure has a selectively closable opening, allowing for reduced lubricating fluid in the axle arm portions and minimizing fluid churning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional axle assemblies use enclosed shoulder joints with lubricating fluid, then the joints are adequately lubricated, but fluid churning increases parasitic losses and heat generation
Solution Approach 1:
The shoulder joint is segmented into two zones: an enclosed portion containing lubricating fluid for reliable lubrication, and an open portion allowing reduced fluid volume. This segmentation reduces fluid churning and parasitic losses while maintaining adequate lubrication in the enclosed portion.
Solution Approach 2:
The shoulder joint structure transitions from a fully enclosed static design to a dynamic hybrid design with both enclosed and open portions. The selectively closable opening allows the system to adapt between enclosed and open states, optimizing performance based on operating conditions.
2Temperature
If the shoulder structure is fully enclosed, then lubricating fluid is contained, but heat generation from fluid churning increases
Solution Approach 1:
The shoulder joint is divided into enclosed and open portions, allowing the lubricating fluid to be confined to a smaller enclosed volume. This reduces the quantity of fluid subject to churning and heat generation while maintaining adequate lubrication where needed.
Solution Approach 2:
The design accepts that some fluid churning will occur in the enclosed portion but converts the potential harm by limiting the fluid volume to only what is necessary for lubrication. The open portion allows excess fluid to be excluded, transforming the problem of fluid volume management into a benefit of reduced heat generation.
3Loss of energy
If the opening in the shoulder structure is permanently open, then fluid churning is reduced, but lubrication reliability deteriorates
Solution Approach 1:
The shoulder joint is segmented into an enclosed portion that maintains lubrication reliability and an open portion that reduces fluid churning. The selective placement of the opening ensures it does not compromise the enclosed lubrication environment.
Solution Approach 2:
The opening is made selectively closable rather than permanently open or closed, allowing the system to dynamically adapt to operating conditions. This enables optimization between reduced fluid churning and maintained lubrication reliability based on actual performance requirements.
Data Source
AI summary
A drive axle assembly having at least one drive shaft tube and at least one substantially horizontal drive shaft located within the tube. The drive shaft is connected at an inboard end to a differential and an outboard end of the drive shaft has a first bevel gear. The first bevel gear is meshed with a second bevel gear within a shoulder structure. The second bevel gear is located on a non-horizontal drive shaft. A selectively closeable opening is provided in the shoulder structure for installing and maintaining the bevel gears.